The present invention relates generally to a device for tensioning traveling yarns and the like.
It is known from the prior art to provide such a device which is utilized to tension a running or traveling yarn in a textile machine. This prior-art device has a yarn passageway made up of three sections. Each of these sections has a progressively larger diameter from the inlet end of the device. A small diameter section at the entrance end of the device has a seat adjacent the inner end thereof, and a spherical element is received on this seat. The medium diameter section surrounds the seat and retains the spherical element therein. The larger diameter section of the passageway is sufficiently large to enable pressurized air to pass over the spherical element without forcing the element out of the end of the passageway. The wall adjacent the junction of the large and medium diameter sections is tapered so as to permit radial return of the spherical element to the medium diameter section to reside on the seat. A mounting arrangement is provided for securing the device to a yarn handling machine. As the yarn passes through the three sections of the yarn passageways, it is engaged in the medium diameter section by the spherical element, which impedes the yarn progress. Thereby, the yarn is tensioned.
The difficulty of this prior-art arrangement is that the spherical element is laterally completely surrounded by the wall bounding the yarn passageway. Lateral displacement of the spherical element to any appreciable extent is possible only if the spherical element moves axially away from the inlet opening to a substantial degree, that is into the passage section having the next larger diameter. This in itself would not be inherently too disadvantageous, except that the fact that the spherical element is laterally completely surrounded by the wall bounding the passageway of course means that the passageway is closed in lateral direction. It has now been found that under these circumstances the passageway becomes rapidly clogged with fibers and the like which prevent the free movement of the spherical element. As soon as there is any interference with this free movement, however, the device is no longer capable of controlling the tension on the yarn, i.e., as acting as a yarn brake with a braking or tensioning effect which is determined by the weight of the spherical element. The prior-art device has a further disadvantage, namely the fact that because of the three-section yarn passageway it must be relatively tall. Still another disadvantage is the fact that despite the lateral closure of the passageway, there is still a danger that the spherical element might fall out of the device under certain circumstances.